Mac Mail Wrongly Sent to Junk

I see no problems with your Junk Mail settings. Is it possible to disable your Rules and reply to the same group email to see if it still goes to junk? It may even be possible to narrow it down to a specific rule if your friends are understanding with the repeated replies while you troubleshoot.

Here are 3 areas I would check:

• Mail > Settings > Junk Mail. Under the section that says "The following types of messages are exempt from junk mail filtering", make sure all options are checked.
• Mail > Settings > Rules. Disable all rules and check or inspect each rule that is active to determine if a rule moved the mail to junk.
• The last area to check is if your mail server is using the IMAP type. IMAP is now the most common type and works by mirroring the mail server mailboxes. If the mail server determines that an email is junk then it is put into its junk folder and your computer is just seeing what is at the mail server before any Junk Filtering is done by your computer. The advantage to using IMAP is that when you delete an email on one device it is also reflected on all others. To check this behavior, you would have to log in to your mail provider from Safari. It may have its own junk filtering options which you can change or turn off. To determine if you are using IMAP, go to Mail > Settings > Accounts, and the type is listed under the mailbox as either IMAP or POP.